Loss of antibodies and response to (re-)vaccination in children after treatment for acute lymphocytic leukemia: a systematic review

Adequate immune responses to vaccines after chemotherapy for leukaemia diagnosed in childhood

AIM

The survival rate after treatment for childhood leukaemia has greatly improved, but could result in protracted immune deficiency. This study examined the immune status of children after chemotherapy and evaluated their responses to immunisation.

METHODS

Subjects who had completed their treatment for acute lymphoblastic leukaemia at The Children's Hospital Reykjavík, Iceland, during 2011-2020 had blood drawn and were then immunised for influenza in October 2021. Blood was drawn again 4 weeks later and their humoral and cellular responses were measured with a haemagglutination inhibition assay and lymphocyte stimulation test. Antibodies to other immunisations were also evaluated.

RESULTS

We studied 18 patients (10 male) who had completed their treatment at 3.7-20.3 years of age (mean 9.1), 11-84 months (mean 36.9) before enrolment. Conventional immunological evaluation did not reveal notable abnormalities. The responses to several childhood vaccinations, including the pneumococcal conjugate vaccination, were adequate in most patients. Humoral responses to the influenza vaccine confirmed adequate reactions in all but one patient. Considerable variations were observed in the lymphocyte stimulations tests.

CONCLUSION

Most patients reacted adequately to immunisation, especially against annual influenza and Streptococcus pneumoniae, reiterating the usefulness of vaccinations. The most appropriate timing for vaccination after treatment still needs to be determined.

Loss of protective anti-HBs titers and seroconversion to hepatitis B vaccination in children during chemotherapy for acute lymphoblastic leukemia

BACKGROUND

This study aimed to evaluate loss of protective anti-hepatitis B (HBs) titers and seroconversion to hepatitis B vaccine (HBV) during chemotherapy in children with acute lymphoblastic leukemia (ALL).

METHODS

Anti-HBs titers were done at diagnosis. Patients were divided into two groups. Group I (protective titers >10 mIU/ml) received single double dose of HBV as booster. Titers were repeated at three time points: end of phase 1b, beginning of re-induction, and start of maintenance chemotherapy. Group II (nonprotective titers <10 mIU/L) received hepatitis B immunoglobulin (HBIG), prior to start of chemotherapy, followed by three double doses of HBV as booster. Titers were repeated at two time points: prior to first dose, and 4 weeks after third dose of vaccine.

RESULTS

Total 125 patients were included: 88 in group I; 37 in group II. Among group I patients, 98.7%, 90%, and 84% retained protective titers at the three points, respectively. Subgroup analysis showed that those with initial titers greater than 100 mIU/L retained protective titers better than those with titers between 11 and 100 mIU/L (p = .0001). Among group II patients, 62% and 64% attained protective titers at the two points, respectively.

CONCLUSIONS

HBV boosters helped maintain protective titers during intensive ALL chemotherapy in immunized children having titers more than 10 mIU/L, and more so if titer was more than 100 mIU/L. Therefore, we propose that cut off for protective anti-HBs titers be changed to greater than or equal to 100 mIU/L. Titers between 11 and 100 mIU/L may require combined active and passive immunization. Around one-third of group II patients who fail to attain protective titers may need frequent doses of HBIG.

Antibody waning after immunosuppressive chemotherapy and immunomodulators, re-immunization considerations in pediatric patients with malignancy and chronic immune thrombocytopenic purpura

Introduction

Immunosuppressive chemotherapy increase the risk of vaccine-preventable infectious diseases in children; nevertheless, chemotherapy may result in delay or miss updated immunization schedules. The predictable antibody waning after incomplete primary immunization series may be intensified at the end of chemotherapy. This study aimed to investigate post-chemotherapy vaccine immunity waning at the end of immunosuppressive therapy in children with malignancy and hematologic disorders.

Materials and methods

Children with malignancies and hematologic disorders including chronic immune thrombocytopenic purpura (ITP) younger than 18 years old were enrolled from September 2015 to August 2019. Eligible patients who completed their treatment protocol for at least 6 months were recruited. The patient information, including sex, age at the date of diagnosis, number of chemotherapy sessions, underlying disease, and vaccination history, was taken by chart review using predefined questionnaires. The patient’s blood samples were obtained, and serum IgG antibody titer checked against diphtheria, tetanus, hepatitis B virus (HBV), mumps, measles, and rubella (MMR) were measured by enzyme-linked immunosorbent assay (ELISA).

Results

110 children receiving immunosuppressive chemotherapy were recruited. Forty-four (40%) of the children tested were girls and 66 (60%) were boys. The mean age of patients was 5.5 years with a range of 2 to 13 years. Of 110 studied children, 27.3% were seronegative for all antibodies. On average, patients undergo 19 episodes of chemotherapy. The mean chemotherapy sessions were significantly greater in children who were seronegative for all tested antibodies (mean: 36.2, 95% CI 33.16 to 39.24, p-value < 0.001). No statistically significant differences were observed regarding the patient’s sex and age between the seropositive and seronegative groups (p-value 0.513 and 0.060, respectively). Based on Poisson regression model analysis, the female gender was associated with 37% lower odds of seronegativity (incidence rate ratio (IIR): 0.63; [95% conf. interval: 0.39 to 1.01, p-value: 0.55]), while chemotherapy sessions 30 or more was associated with significant odds of seronegativity for all tested vaccines (IIR: 25.41; [95% conf. interval: 6.42 to 100.57, p-value < 0.001]).

Conclusion

Our results reemphasized planned catchup immunization in children undergoing immunosuppressive chemotherapy for malignancy, especially against tetanus, diphtheria, and hepatitis B at least 6 months after the end of chemotherapy sessions.

Diagnosis and Management of Opsoclonus-Myoclonus-Ataxia Syndrome in Children: An International Perspective

BACKGROUND AND OBJECTIVES

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare disorder of the nervous system that classically presents with a combination of characteristic eye movement disorder and myoclonus, in addition to ataxia, irritability, and sleep disturbance. There is good evidence that OMAS is an immune-mediated condition that may be paraneoplastic in the context of neuroblastoma. This syndrome may be associated with long-term cognitive impairment, yet it remains unclear how this is influenced by disease course and treatment. Treatment is largely predicated on immune suppression, but there is limited evidence to indicate an optimal regimen.

METHODS

Following an international multiprofessional workshop in 2004, a body of clinicians and scientists comprising the International OMS Study group continued to meet biennially in a joint professionals and family workshop focusing on pediatric OMAS. Seventeen years after publication of the first report, a writing group was convened to provide a clinical update on the definitions and clinical presentation of OMAS, biomarkers and the role of investigations in a child presenting with OMAS, treatment and management strategies including identification and support of long-term sequelae.

RESULTS

The clinical criteria for diagnosis were reviewed, with a proposed approach to laboratory and radiologic investigation of a child presenting with possible OMAS. The evidence for an upfront vs escalating treatment regimen was reviewed, and a treatment algorithm proposed to recognize both these approaches. Importantly, recommendations on monitoring of immunotherapy response and longer-term follow-up based on an expert consensus are provided.

DISCUSSION

OMAS is a rare neurologic condition that can be associated with poor cognitive outcomes. This report proposes an approach to investigation and treatment of children presenting with OMAS, based on expert international opinion recognizing the limited data available.

Molecular characterization of hepatitis B virus (HBV) isolated from a pediatric case of acute lymphoid leukemia, with a delayed response to antiviral treatment: a case report

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is effectively used as the first-line antiviral for chronic hepatitis B virus (HBV) infection in adults and children older than 12 years. To date, no confirmed case of virologic breakthrough (VBT) in a pediatric case has been reported.

CASE PRESENTATION

Here we describe a case of a 5-year old, asymptomatically infected with HBV infection two months after chemotherapy for precursor B acute lymphoblastic leukemia (ALL). Although the 5-year old male is South African, his family originated from Guinea. At the end of the one-year follow-up, the infection progressed to chronic HBV infection, with a high viral load. At 36 weeks (8 months) post-treatment with lamivudine (LAM), there was a partial virologic response (PVR) and after 61 weeks (14 months), he was switched to TDF rescue monotherapy. Even with TDF treatment, he still experienced VBT and subsequent PVR. The full-length genome of HBV isolated 78 weeks after the switch to rescue TDF monotherapy was sequenced and belonged to genotype E. In addition to the LAM mutations (rtS256G and rtM267L), missense mutations in B-cell, T-cell, HLA class I and II-restricted epitopes emerged, which were to evade and escape host surveillance, leading to delayed viral clearance, persistence and disease progression. Two further events of VBT occurred between weeks 113 and 141 of TDF rescue-therapy. Viral loads and liver enzymes are normalizing progressively with long-term therapy.

CONCLUSION

Although the host immune reconstitution may be delayed, prolonged TDF treatment was effective in treating this pediatric case of HBV infection with VBT and PVR.

Cutaneous diphtheria complicated oncologic reconstruction surgery in osteosarcoma

Diphtheria is an uncommon bacterial infection of the upper respiratory tract. We described a surgical site infection in a young adolescent female on maintenance chemotherapy. Corynebacterium diphtheriae was recovered from the wound, and she was treated with antibiotics and antitoxin. Cutaneous diphtheria should be considered in immunocompromised patients receiving chemotherapy.

CD38-Directed Vincristine Nanotherapy for Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Although intensive chemotherapy greatly improved the survival rate, it is often accompanied by severe and lifelong side effects as a result of weak ALL selectivity. The intensive and poorly selective chemotherapy is also detrimental to patients' immune system. There is an urgent need to develop more selective and less toxic chemotherapy for ALL. Here, we report daratumumab-polymersome-vincristine (DP-VCR) as a CD38-directed nanotherapy for ALL. DP-VCR showed selective uptake in CD38-positive 697 and Nalm-6-Luc ALL cells and potent anti-ALL activity with an IC₅₀ as low as 0.06 nM VCR, which was 13.7-fold more potent than free VCR. In contrast, no toxicity to human peripheral blood mononuclear cells was detected for DP-VCR even at 108.3 nM VCR. The apoptotic assays confirmed a high selectivity of DP-VCR to CD38-positive ALL cells. DP-VCR exhibited superior treatment of both 697 and Nalm-6-Luc orthotopic ALL models to all controls, as revealed by significant survival benefit and marked reduction of leukemia burden in bone marrow, blood, spleen, and liver. Importantly, DP-VCR induced few side effects. DP-VCR emerges as a safe and potent nanotherapy for CD38-positive ALL.

Pneumococcal vaccination during chemotherapy in children treated for acute lymphoblastic leukemia

BACKGROUND

Children treated for acute lymphoblastic leukemia (ALL) are at high risk of invasive pneumococcal disease (IPD). We assessed immunity to S. pneumoniae among children after ALL treatment, and the impact of pneumococcal immunization during and after chemotherapy.

METHODS

We performed an observational retrospective study of children treated for ALL at a single center. All children were fully immunized with three routine doses of pneumococcal conjugate vaccine (PCV) prior to ALL diagnosis. Children from Group 1 received a 13-valent PCV (PCV13) dose during the maintenance phase as well as a PCV13 booster after completing chemotherapy, while Group 2 only received the postchemotherapy dose. Serologic testing was performed after chemotherapy and again after the postchemotherapy dose. A serotype-specific antibody level ≥0.35 μg/ml was considered protective, and patients with protective levels for ≥70% of serotypes in the PCV7 vaccine were defined as seroprotected.

RESULTS

A total of 71 children (median age 46 months, range 12-160) were included. At the end of chemotherapy, 53.1% of children in Group 1 (17/32) and 25.6% in Group 2 (10/39) were seroprotected (p = .018). After the postchemotherapy booster, seroprotection rates increased to 96.9% in Group 1 (31/32) and 100% in Group 2.

CONCLUSIONS

Rates of pneumococcal seroprotection among children with ALL are low following chemotherapy, despite prior routine immunization. A PCV booster during chemotherapy may shorten the period of susceptibility to IPD in some children. However, irrespective of a booster during chemotherapy, a PCV dose postchemotherapy appears sufficient to confer high rates of seroprotection against IPD.

Waning Vaccine Immunity and Vaccination Responses in Children Treated for Acute Lymphoblastic Leukemia: A Canadian Immunization Research Network Study

BACKGROUND

There is no uniform guideline for postchemotherapy vaccination of children with acute lymphoblastic leukemia (ALL). We evaluated waning immunity to 14 pneumococcal serotypes, pertussis toxin (PT), tetanus toxoid (TT) and varicella, and immunogenicity of postchemotherapy diphtheria, tetanus, pertussis, hepatitis B, polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) and pneumococcal vaccination among previously vaccinated children treated for ALL.

METHODS

This was a multicenter trial of children with ALL enrolled 4-12 months postchemotherapy completion. Exclusion criteria included: infant ALL, relapsed ALL, and stem cell transplant recipients. Immunocompetent children were recruited as controls. Postchemotherapy participants received DTaP-IPV-Hib and 13-valent pneumococcal conjugate vaccine (PCV13) concurrently, followed by 23-valent pneumococcal polysaccharide vaccine (PPV23) 2 months later. Serology was measured at baseline, 2 and 12 months postvaccination. Adverse events were captured via surveys.

RESULTS

At enrollment, postchemotherapy participants (n = 74) were less likely than controls (n = 78) to be age-appropriately immunized with DTaP (41% vs 89%, P < .001) and PCV (59% vs 79%, P = .008). Geometric mean concentrations (GMCs) to TT, PT, PCV serotypes, and varicella were lower in postchemotherapy participants than controls after adjusting for previous vaccine doses (P < .001). Two months postvaccination, GMCs to TT, PT, and PCV serotypes increased from baseline (P < .001 for all antigens) and remained elevated at 12 months postvaccination. Antibody levels to PPV23 serotypes also increased postvaccination (P < .001). No serious adverse events were reported.

CONCLUSIONS

Children treated for ALL had lower antibody levels than controls against pneumococcal serotypes, tetanus, pertussis, and varicella despite previous vaccination. Postchemotherapy vaccination with DTaP-IPV-Hib, PCV13, and PPV23 was immunogenic and well tolerated. Children with ALL would benefit from systematic revaccination postchemotherapy.

CLINICAL TRIALS REGISTRATION

NCT02447718.

Immune function in childhood cancer survivors: a Children's Oncology Group review

Childhood cancer and its treatment often impact the haematopoietic and lymphatic systems, with immunological consequences. Immunological assessments are not routinely included in surveillance guidelines for most survivors of childhood cancer, although a robust body of literature describes immunological outcomes, testing recommendations, and revaccination guidelines after allogeneic haematopoietic cell transplantation. Survivorship care providers might not fully consider the impaired recovery of a child's immune system after cancer treatment if the child has not undergone haematopoietic cell transplantation. We did a scoping review to collate the existing literature describing immune function after childhood cancer therapy, including both standard-dose chemotherapy and high-dose chemotherapy with haematopoietic cell rescue. This Review aims to summarise: the principles of immunology and testing of immune function; the body of literature describing immunological outcomes after childhood cancer therapy, with an emphasis on the risk of infection, when is testing indicated, and preventive strategies; and knowledge gaps and opportunities for future research.

Casting a wider protective net: Anti-infective vaccine strategies for patients with hematologic malignancy and blood and marrow transplantation

Patients who have hematologic malignancies are at high risk for infections but vaccinations may be effective prophylaxis. The increased infection risk derives from immune defects secondary to malignancy, the classic example being CLL, and chemotherapies and immunotherapy used to treat the malignancies. Therapy of hematologic malignancies is being revolutionized by introduction of novel targeted agents and immunomodulatory medications, improving the survival of patients. At the same time those agents uniquely change the infection risk and response to immunizations. This review will summarize current vaccine recommendations for patients with hematologic malignancies including patients who undergo hematopoietic cell transplant.

Immunization status and re-immunization of childhood acute lymphoblastic leukemia survivors

Intensive chemotherapy can cause long-lasting immunosuppression in children who survived cancer. The immunosuppression varies according to the type of cancer, intensity of chemotherapy and age of the patient. A sufficient immune reconstruction when has been completed in childhood cancer survivors, the re-vaccination program can achieve sufficient antibody levels for some of the life-threatening vaccine-preventable infectious diseases. This study evaluates the serological status of pediatric acute lymphoblastic leukemia (ALL) cases before and after the intensive chemotherapy treatment. Antibodies against measles, mumps, rubella, varicella, hepatitis A and B were tested with the enzyme-linked immunosorbent assay (ELISA) method. Antibody titers were measured firstly at the leukemia diagnosis time when the chemotherapy was not started. The second evaluation of antibody titers was studied at 6 months after the cessation of chemotherapy for all patients. Forty-six patients with the mean age of 6.1 ± 4.5 years were participated in this study. Changing to seronegative after treatment was significantly different in measles, rubella, hepatitis A and hepatitis B (p < .05). Seventy-eight (28%) antibody levels in the patients were non-protective for all diseases. Only three (7%) patients had protective antibody levels for all diseases in the sixth month of chemotherapy cessation. There was a negative correlation between patient's age and losing protective antibody levels for any vaccine-preventable disease (p < .05). Antibody levels against vaccine-preventable diseases have evident that reduced after ALL treatment at childhood. Pediatric ALL survivors must be re-vaccinated for vaccine-preventable diseases after achieving immune reconstruction.

Thirteen-Valent Pneumococcal Conjugate Vaccine in Children With Acute Lymphoblastic Leukemia: Protective Immunity Can Be Achieved on Completion of Treatment

BACKGROUND

Children with acute lymphoblastic leukemia (ALL) are at increased risk of developing invasive pneumococcal disease. This study describes the immunogenicity of 13-valent pneumococcal conjugate vaccine (PCV13) during and after chemotherapy.

METHODS

Children with ALL were allocated to study groups and received a single dose of PCV13: group 1, maintenance chemotherapy; group 2, end of chemotherapy; group 3, 6 months after chemotherapy. A protective vaccine response was defined as at least 10 of 12 serotypes (or >83% of serotypes with data) achieving postvaccination serotype-specific immunoglobulin G ≥0.35 µg/mL and ≥4-fold rise, compared to prevaccination at 1 and 12 months.

RESULTS

One hundred eighteen children were recruited. Only 12.8% (5/39; 95% confidence interval [CI], 4.3%-27.4%) of patients vaccinated during maintenance (group 1) achieved a protective response at 1 month postvaccination and none had a protective response at 12 months. For group 2 patients, 59.5% (22/37; 95% CI, 42.1%-75.3%) achieved a response at 1 month and 37.9% (11/29; 95% CI, 20.7%-57.7%) maintained immunity at 12 months. For group 3 patients, 56.8% (21/37; 95% CI, 39.5%-72.9%) achieved a protective response at 1 month and 43.3% (13/30; 95% CI, 25.5%-62.6%) maintained immunity at 12 months.

CONCLUSIONS

This study demonstrated that the earliest time point at which protective immunity can be achieved in children with ALL is on completion of chemotherapy. This is earlier than current recommendations and may improve protection during a period when children are most susceptible to infection.

CLINICAL TRIALS REGISTRATION

EudraCT 2009-011587-11.

Treatment and revaccination of children with paraneoplastic opsoclonus-myoclonus-ataxia syndrome and neuroblastoma: The Memorial Sloan Kettering experience

OBJECTIVE

To review the treatment and revaccination of neuroblastoma-associated opsoclonus-myoclonus-ataxia syndrome (OMAS) patients at Memorial Sloan Kettering Cancer Center (MSK).

PROCEDURE

Institutional Review Board approval was obtained for this retrospective study of patients with neuroblastoma-associated OMAS followed at MSK from 2000 to 2016.

RESULTS

Fourteen patients (nine female) were 9-21 (median 17) months old at diagnosis of neuroblastoma and OMAS syndrome. They had stage 1 (n = 12), stage 2B, or intermediate-risk stage 4. Tumor histology was favorable in 11 patients, unfavorable in two, and unknown in one patient. No patient had amplified MYCN. All patients underwent tumor resection at diagnosis. Anti-neuroblastoma treatment was limited to chemotherapy in one patient. Overall survival is 100% at 3-16 (median 10) years. For OMAS, 13 patients received intravenous immune globulin (IVIg), adrenocorticotropic hormone (ACTH), and rituximab, and one received ACTH and IVIg. Seven patients experienced OMAS relapse. For these relapses, five patients received low-dose cyclophosphamide and two received rituximab. The mean total OMAS treatment was 20-96 (median 48) months. Seven patients started rituximab ≤3 months from diagnosis and did not relapse. The other six experienced OMAS relapse. To date, six patients have been revaccinated at a minimum of 2 years after completion of OMAS therapy without OMAS recurrence.

CONCLUSIONS

Patients with neuroblastoma-associated OMAS had excellent overall survival. Early initiation of rituximab, IVIg, and ACTH may reduce risks of OMAS relapse. Revaccination can be resumed without exacerbation of OMAS. Further investigation with a larger cohort of patients is needed.

Immune reconstitution in children following chemotherapy for acute leukemia

Although survival rates for pediatric acute lymphoblastic leukemia are now excellent, this is at the expense of prolonged chemotherapy regimens. We report the long-term immune effects in children treated according to the UK Medical Research Council UKALL 2003 protocol. Peripheral blood lymphocyte subsets and immunoglobulin levels were studied in 116 participants, at six time points, during and for 18-month following treatment, with 30-39 patients analyzed at each time point. Total lymphocytes were reduced during maintenance chemotherapy and remained low 18 months following treatment completion. CD4 T cells remained significantly reduced 18 months after treatment, but CD8 cells and natural killer cells recovered to normal values. The fall in naïve B-cell numbers during maintenance was most marked, but numbers recovered rapidly after cessation of treatment. Memory B cells, particularly nonclass-switched memory B cells, remained below normal levels 18 months following treatment. All immunoglobulin subclasses were reduced during treatment compared to normal values, with IgM levels most affected. This study demonstrates that immune reconstitution differs between lymphocyte compartments. Although total B-cell numbers recover rapidly, disruption of memory/naïve balance persists and T-cell compartment persist at 18 months. This highlights the impact of modern chemotherapy regimens on immunity, and thus, infectious susceptibility and response to immunization.

Post-Chemotherapy Titer Status and Need for Revaccination After Treatment for Childhood Cancer

Objectives. To evaluate the strategy of checking vaccine titers after completion of chemotherapy. Study Design. Retrospective review of pediatric oncology patients who completed chemotherapy. Demographics, post-chemotherapy titers, and absolute lymphocyte counts (ALCs) were analyzed. Results. Ninety patients met inclusion criteria, and 87% of patients had at least one titer checked. Comparing patients <7 years and those ≥7 years at diagnosis, there was no difference in incidence of negative titers except mumps; those <7 years old were more likely to have negative titers (58% vs 20%, P = .003). Comparing those <13 years old to ≥13 years old, there was no difference in negative titers except mumps (45% vs 19%, P = .02) and tetanus (44% vs 0%, P = .002). No patient maintained all protective titers after completion of chemotherapy. Time to ALC recovery was not predictive of positive titers. Conclusion. Checking titers after chemotherapy is not recommended. Providers should assume loss of immunity.

The Impact of Chemotherapy after Pediatric Malignancy on Humoral Immunity to Vaccine-Preventable Diseases

Background/Aim

The antibody titer of vaccine-preventable diseases in pediatric patients who underwent chemotherapy was assessed in order to evaluate the seroprotection after treatment and the feasibility and the efficacy of a policy of revaccination.

Methods

Serum antibody titers of 55 patients for hepatitis B (HBV), rubella, varicella-zoster (VZV), measles, mumps, polio viruses, Clostridium tetani (C. tetani) and Streptococcus pneumoniae (S. pneumoniae) were analysed.

Results: After chemotherapy, a lack of protective antibody titers against HBV, rubella, VZV, measles, mumps, polio viruses, C. tetani, and S. pneumoniae was found in 53%, 45%, 46%, 46%, 43%, 21–26%, 88% and 55% of patients, respectively. In 49 of 55 patients who were tested both before and after chemotherapy for at least a pathogen, the loss of immunity for HBV, rubella, VZV, measles, mumps, polio viruses and C. tetani was respectively 39%, 43%, 38%, 42%, 32%, 33%, and 80%. A low number of B-lymphocytes was associated with the loss of immunity against measles (p=0.04) whereas a high number of CD8+ T-lymphocytes was associated with the loss of immunity against VZV (p=0.03). A single booster of vaccine dose resulted in a seroprotection for HBV, rubella, VZV, measles, mumps, polio viruses, C. tetani and S. pneumoniae in 67%, 83%, 80%, 67%, 33%, 100%, 88% and 67% of patients, respectively.

Conclusions

We confirm that seroprotection for vaccine-preventable diseases is affected by treatment for pediatric malignancy. A single booster dose of vaccine might be a practical way to restore vaccine immunity in patients after chemotherapy.

Infections as a potential long-term risk following childhood leukemia

Leukemia is the most common childhood cancer. While infections are a frequent and potentially severe complication while on treatment, less is known about the risk for infections following therapy completion. In this article, we propose that leukemia survivors might be at increased risk of infections following therapy completion than the general population, independently of potential confounders such as age, sex and Down syndrome. This association is conceivably due to several factors. First, therapy-induced immune dysfunction of both the humoral and cellular compartments appears to last for several years following anti-cancer therapy and after hematopoietic stem cell transplantation. Second, clinical and epidemiological research has shown leukemia survivors are disproportionally affected by comorbidities related to leukemia treatment and its complications, such as diabetes and obesity, which may induce secondary immunodeficiency and infections. Last, differences in health-related behaviors between leukemia survivors and the general population (such as re-vaccination practices) may affect the baseline risk of infections. Although under-represented in the epidemiological literature as a possible late effect of childhood leukemia and its treatment, it is plausible that leukemia survivors are at increased risk of infections for several years when compared to the general population and their siblings. Further research is needed to empirically test these hypotheses.

Long-Term Risk of Infections After Treatment of Childhood Leukemia: A Population-Based Cohort Study Using Administrative Health Data

PURPOSE

Infections are a frequent complication during childhood leukemia treatment. Little is known about the infectious risk in survivors. We compared the relative rate (RR) of infections after treatment completion between pediatric leukemia survivors and the general population.

METHODS

We performed a retrospective, population-based cohort study of children diagnosed with leukemia between 1992 and 2015 in Ontario, Canada, who were alive and relapse free 30 days after treatment completion (index date). Leukemia survivors were matched 5:1 with the general population by year of birth, sex, and rural status and stratified by initial treatment, including and excluding hematopoietic stem-cell transplantation (HSCT). The primary outcome was time to infections, as identified using validated diagnostic codes from administrative databases. Individuals were censored at the earliest of death, first relapse, loss to follow-up, or end of study.

RESULTS

A total of 2,204 leukemia survivors were included and matched with 11,020 controls. The rate of infections was elevated after treatment completion compared with controls (RR, 1.51; 95% CI, 1.45 to 1.57) and at less than 1 year (RR, 1.77; 95% CI, 1.69 to 1.86); 1 to 4.99 years (RR, 1.66; 95% CI, 1.62 to 1.71), and 5 or more years (RR, 1.29; 95% CI, 1.22 to 1.36) from the index date. Among those whose initial treatment excluded HSCT, the rate remained elevated more than 5 years from the index date (RR, 1.29; 95% CI, 1.23 to 1.35). Infection-related death was significantly increased in leukemia survivors both among the entire cohort (hazard ratio, 149.3; 95% CI, 20.4 to 1,091.9) and among those without HSCT (hazard ratio, 92.7; 95% CI, 12.4 to 690.7).

CONCLUSION

A significant association was found between a history of leukemia therapy and an increased risk of infections. Additional study is needed to establish which exposures in patients with leukemia lead to late infections.

Preventing Measles in Immunosuppressed Cancer and Hematopoietic Cell Transplantation Patients: A Position Statement by the American Society for Transplantation and Cellular Therapy

Until recently, measles exposures were relatively rare and so, consequently, were an afterthought for cancer patients and/or blood and marrow transplant recipients and their providers. Declines in measles herd immunity have reached critical levels in many communities throughout the United States due to increasing vaccine hesitancy, so that community-based outbreaks have occurred. The reemergence of measles as a clinical disease has raised serious concerns among immunocompromised patients and those who work within the cancer and hematopoietic cell transplantation (HCT) community. Since live attenuated vaccines, such as measles, mumps, and rubella (MMR), are contraindicated in immunocompromised patients, and with no approved antiviral therapies for measles, community exposures in these patients can lead to life-threatening infection. The lack of data regarding measles prevention in this population poses a number of clinical dilemmas. Herein specialists in Infectious Diseases and HCT/cellular therapy endorsed by the American Society of Transplant and Cellular Therapy address frequently asked questions about measles in these high-risk cancer patients and HCT recipients and provide expert opinions based on the limited available data.

Postchemotherapy Immunization Practices for Non-HSCT Pediatric Oncology Patients

Pediatric oncology patients treated with antineoplastic therapy have impaired immune systems that lead to loss of protective antibodies. They require reimmunization to protect against vaccine-preventable diseases. There are a paucity of studies on the clinical practice of pediatric oncologists and the available recommendations are heterogenous. This study describes current reimmunization practices among pediatric oncologists. We surveyed the Children's Oncology Group (COG)-identified principle investigators to capture clinical practices among pediatric oncologists within their institutions regarding reimmunization of non-hematopoietic stem cell transplantation patients. The majority of respondents did not routinely assess vaccine-related immune status; those who did most frequently assessed 6 months after cessation of therapies. Methods of assessment included type of therapy received, vaccine titers, and absolute lymphocyte counts. Providers from smaller institutions were more likely to check vaccine titers than those from larger institutions. More than half of the surveyed institutions did not have standardized guidelines available for practitioners. There are variations in reimmunization practices among pediatric oncologists despite available guidelines on recommended schedules. Further research is needed to identify the safest and most cost-effective way to insure immunity to infectious disease after the treatment of childhood cancer.

Vaccination of patients with haematological malignancies who did not have transplantations: guidelines from the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Patients with haematological malignancies are at high risk of infection because of various mechanisms of humoral and cell-mediated immune deficiencies, which mainly depend on underlying disease and specific therapies. Some of these infections are vaccine preventable. However, these malignancies are different from each other, and the treatment approaches are diverse and rapidly evolving, so it is difficult to have a common programme for vaccination in a haematology ward. Additionally, because of insufficient training about the topic, vaccination is an area often neglected by haematologists, and influenced by cultural differences, even among health-care workers, in compliance to vaccines. Several issues are encountered when addressing vaccination in haematology: the small size of the cohorts that makes it difficult to show the clinical benefits of vaccination, the subsequent need to rely on biological parameters, their clinical pertinence not being established in immunocompromised patients, scarcity of clarity on the optimal timing of vaccination in complex treatment schedules, and the scarcity of data on long-term protection in patients receiving treatments. Moreover, the risk of vaccine-induced disease with live-attenuated vaccines strongly limits their use. Here we summarise guidelines for patients without transplantations, and address the issue by the haematological group-myeloid and lymphoid-of diseases, with a special consideration for children with acute leukaemia.

Humoral immune response of childhood acute lymphoblastic leukemia survivors against the measles, mumps, and rubella vaccination

BACKGROUND

There is a great risk of infection with viral-vaccine-preventable diseases like measles, mumps, and rubella (MMR) infections after the end of chemotherapy treatment of children with acute lymphoblastic leukemia (ALL), which could have been prevented with MMR vaccination. Previous studies reported widely variable rates of seropositivity (seroprotection) for MMR after ALL treatment ends. Also, few studies evaluated the response to MMR booster vaccinations after the end of ALL treatment and reported unclear and difficult to interpret results.

MATERIAL AND METHODS

This retrospective cross-sectional study evaluated the prevalence of seropositive (protection) antibody titer levels for MMR among ALL childhood survivors who were followed-up at Jeddah Oncology Center, Saudi Arabia. The aim of the study was also to investigate and analyze the response of seronegative patients to a booster MMR vaccination.

RESULTS

Fifty-seven ALL children were evaluated. Thirty-five patients (61.4%) were seropositive/seroprotected and the remaining 22 patients (38.6%) were seronegative for MMR. ALL Children under the age of 5 years had a higher prevalence of seronegative titers. Interestingly, the prevalence of seroprotection decreased as the time interval increased post-treatment, while seroconversion rates after administering a booster MMR vaccine were 57.1%, 87.5%, and 78.6%, respectively for MMR.

CONCLUSION

We suggest the need for booster MMR vaccination, especially for ALL children under the age of 5 years and those who experienced a protracted time interval post-treatment.

Measles Outbreak in Pediatric Hematology and Oncology Patients in Shanghai, 2015

Background:

Despite substantial progress toward measles control are making in China, measles outbreaks in immunocompromised population still pose a challenge to interrupt endemic transmission. This study aimed to investigate the features of measles in pediatric hematology and oncology patients and explore the reasons behind the outbreak.

Methods:

We collected demographic, epidemiological, and clinical data of immunocompromised measles children. All suspected measles cases were laboratory-confirmed based on the presence of measles IgM and/or identification of measles RNA. The clinical data were statistically analyzed by t-test for continuous variables and Fisher's exact test for categorical variables.

Results:

From March 9 to July 25 in 2015, a total of 23 children with malignancies and post hematopoietic stem cell transplantation (post-HSCT) were notified to develop measles in Shanghai. Of these 23 patients with the median age of 5.5 years (range: 11 months–14 years), 20 (87.0%) had received 1–3 doses of measles vaccine previously; all patients had fever with the median fever duration of 8 days; 21 (91.3%) had cough; 18 (78.3%) had rash; 13 (56.5%) had Koplik's spot; 13 (56.5%) had complications including pneumonia and acute liver failure; and five (21.7%) vaccinated patients died from severe pneumonia or acute liver failure. Except the first patient, all patients had hospital visits within 7–21 days before measles onset and 20 patients were likely to be exposed to each other.

Conclusions:

The outcome of measles outbreak in previously vaccinated oncology and post-HSCT pediatric patients during chemotherapy and immunosuppressant medication was severe. Complete loss of protective immunity induced by measles vaccine during chemotherapy was the potential reason. Improved infection control practice was critical for the prevention of measles in malignancy patients and transplant recipients.

Vaccination in immunocompromised host: Recommendations of Italian Primary Immunodeficiency Network Centers (IPINET)

Infectious complications are a major cause of morbidity and mortality in patients with primary or secondary immunodeficiency. Prevention of infectious diseases by vaccines is among the most effective healthcare measures mainly for these subjects. However immunocompromised people vary in their degree of immunosuppression and susceptibility to infection and, therefore, represent a heterogeneous population with regard to immunization. To date there is no well- established evidence for use of vaccines in immunodeficient patients, and indications are not clearly defined even in high-quality reviews and in most of the guidelines prepared to provide recommendations for the active vaccination of immunocompromised hosts. The aim of this document is to issue recommendations based on published literature and the collective experience of the Italian primary immunodeficiency centers, about how and when vaccines can be used in immunocompromised patients, in order to facilitate physician decisions and to ensure the best immune protection with the lowest risk to the health of the patient.

Dynamic re-immunization of off-treatment childhood cancer survivors: An implementation feasibility study

There are no universally approved re-vaccination guidelines for non-transplant pediatric cancer survivors. We hypothesized that by utilizing a response-based re-vaccination schedule, we could tailor vaccine schedules in off-treatment cancer survivors. Pre-vaccination antibody levels were obtained in 7 patients at an average of 20 days after the end of treatment date. In those without protective antibody levels, we administered vaccines 3 months after completion of treatment. Revaccinating patients 3 months after the end of treatment date resulted in protective antibody levels for most vaccines. We showed, on a preliminary basis, that vaccinating non-transplanted pediatric cancer survivors can be dynamically implemented in children with recovering immune function.

Immunization status in childhood cancer survivors: A hidden risk which could be prevented

BACKGROUND

A limited number of studies have examined the vaccine-specific antibody status of children with cancer. There are disagreements over the guidelines for postcancer immunization strategy.

METHODS

Our study was an observational, cross-sectional retrospective review of data collected on children who were seen in the outpatient clinic at King Abdullah Medical City, Oncology Center, Jeddah, the Kingdom of Saudi Arabia. Our aim was to evaluate the seropositive status to vaccine-preventable diseases: measles, mumps, rubella, diphtheria, tetanus, polio, and Haemophilus influenzae type B (HIB) in childhood cancer survivors at our center in order to plan future vaccination for these children and establish a simple revaccination schedule.

RESULTS

Forty-seven patients (21 boys and 26 girls) were included in the study. Age at the time of cancer diagnosis (mean±standard deviation) was 5.68±3.79 years and age at test sampling was 10.68±3.79 years. Acute leukemia was the most common cancer (49% of patients), followed by lymphoma (28%), brain tumors (13%), and solid tumors (10%). Treatment intensities (according to the Treatment Intensity Rating Scale, version 3.0; ITR-3) were 2, 3, and 4 for 26 patients (55%), 20 patients (43%), and one patient (2.1%), respectively. We found that 93% of our patients were considered seronegative (unprotected) for at least one vaccine-preventable disease. The seronegative rates for measles, mumps, rubella, diphtheria, tetanus, polio, and HIB were 46.8%, 36.2%, 36.2%, 46.8%, 61.7%, 17.1%, and 42.6%, respectively. Criteria including age at diagnosis, age at sampling, type of malignancy, and treatment intensity were not significantly different between seropositive and seronegative patients.

CONCLUSION

Seronegative rates for vaccine-preventable diseases were very high in childhood cancer survivors, which represented a subpopulation of high-risk patients who could benefit from revaccination. We suggest a universal revaccination approach for all childhood cancer survivors, which is easily applicable and of low cost.

An unexpected tetanus case

1 million cases of tetanus are estimated to occur worldwide each year, with more than 200 000 deaths. Tetanus is a life-threatening but preventable disease caused by a toxin produced by Clostridium tetani-a Gram-positive bacillus found in high concentrations in soil and animal excrement. Tetanus is almost completely preventable by active immunisation, but very rarely unexpected cases can occur in individuals who have been previously vaccinated. We report a case of generalised tetanus in a 22-year-old woman that arose despite the protective antitoxin antibody in her serum. The patient received all her vaccinations in the USA; her last vaccination was 6 years ago. The case was unusual because the patient had received all standard vaccinations, had no defined port of entry at disease onset, and had symptoms lasting for 6 months. Tetanus can present with unusual clinical forms; therefore, the diagnosis and management of this rare but difficult disease should be updated. In this Grand Round, we review the clinical features, epidemiology, treatment, and prognosis of C tetani infections.

Understanding the reconstitution of the B-cell compartment in bone marrow and blood after treatment for B-cell precursor acute lymphoblastic leukaemia

A better understanding of the reconstitution of the B-cell compartment during and after treatment in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) will help to assess the immunological status and needs of post-treatment BCP-ALL patients. Using 8-colour flow cytometry and proliferation-assays, we studied the composition and proliferation of both the B-cell precursor (BCP) population in the bone marrow (BM) and mature B-cell population in peripheral blood (PB) during and after BCP-ALL therapy. We found a normal BCP differentiation pattern and a delayed formation of classical CD38^dim -naive mature B-cells, natural effector B-cells and memory B-cells in patients after chemotherapy. This B-cell differentiation/maturation pattern was strikingly similar to that during initial B-cell development in healthy infants. Tissue-resident plasma cells appeared to be partly protected from chemotherapy. Also, we found that the fast recovery of naive mature B-cell numbers after chemotherapy was the result of increased de novo BCP generation, rather than enhanced B-cell proliferation in BM or PB. These results indicate that post-treatment BCP-ALL patients will eventually re-establish a B-cell compartment with a composition and B-cell receptor repertoire similar to that in healthy children. Additionally, the formation of a new memory B-cell compartment suggests that revaccination might be beneficial after BCP-ALL therapy.

Protection against vaccine preventable diseases in children treated for acute lymphoblastic leukemia

BACKGROUND

The objective of this retrospective study was to assess protection against vaccine preventable diseases (VPDs) in children treated for acute lymphoblastic leukemia (ALL).

PROCEDURE

Clinical characteristics and vaccination records were collected. Antibodies against VPDs were measured after completion of chemotherapy and after a booster dose of vaccine. Immunization status of household members was evaluated.

RESULTS

Sixty children were included. Median interval between the end of chemotherapy and enrolment in the study was 13 months (range 1-145). At ALL diagnosis, 81.3% of the children were up to date with their vaccination schedule. This proportion decreased to 52.9% at enrolment. Among the parents, 21% were up to date with their immunization schedule and 42% had received seasonal influenza vaccination. After chemotherapy, less than 50% of the patients were seroprotected against tetanus, diphtheria, polio 3, Haemophilus influenzae type b (Hib), and mumps and no more than 80% were seroprotected against polio 1 and 2, measles, rubella, and varicella. After a booster dose of vaccine, the rate of protection increased to over 90% for each of the following antigens: TT, DT, polio 1, Hib, measles, and rubella. Nevertheless, polio 3, mumps, and varicella-zoster virus antibodies titers/concentrations remained below seroprotective thresholds in over 20% of the patients.

CONCLUSIONS

After chemotherapy for ALL, most of the children were not protected against VPDs. As the majority mounted a robust response to booster vaccines, efforts need to be done to improve protection against VPDs by implementing a systematic vaccine booster schedule. This could also be helped by reinforcing household members' immunization.

Immune Dysfunction After Completion of Childhood Leukemia Therapy

BACKGROUND

Children with leukemia suffer immune dysfunction from their malignancy and chemotherapy. The immune system components most affected, the degree to which immune suppression occurs, and the duration of immunodeficiency are incompletely characterized. This study measures immunologic parameters following completion of therapy.

METHODS

This is a prospective, single institution cohort study. Eligible children with acute myelogenous or acute lymphoblastic leukemia diagnosed between 1 and 21 years of age were enrolled at therapy completion. Immune parameters were assessed at the end of therapy and 6 months later: complete blood counts, immunoglobulin levels, quantitative lymphocyte subsets, mitogen-induced lymphocyte proliferation, natural killer cell function, and vaccine titers.

RESULTS

Twenty patients were evaluated; 13 (65%) were female, 15 had acute lymphoblastic leukemia (75%). Mean age at diagnosis was 7.9 years. At end of therapy, all patients had some degree of immune dysfunction. At 6 months posttherapy, persistent abnormalities included: leukopenia (25%), neutropenia (15%), lymphopenia (5%), hypogammaglobulinemia (25%), one or more subtherapeutic vaccine titers (100%), abnormal lymphocyte subset levels (20%), decreased (15%), or absent (10%) natural killer cell function and abnormal lymphocyte proliferative responses (25%).

CONCLUSIONS

All patients had multiple abnormalities at end of therapy, and all patients had some degree of persistent immune dysfunction at 6 months after completion of therapy. Clinical implications of these laboratory abnormalities are currently unknown; longer term evaluations are ongoing. We demonstrate that survivors of childhood cancer have lasting quantitative and functional immunologic defects and may remain at risk for infectious complications after completion of therapy.

Immunization practices in acute lymphocytic leukemia and post-hematopoietic stem cell transplant in Canadian Pediatric Hematology/Oncology centers

There are no Canadian immunization guidelines for children treated for malignancy. Guidelines do exist for patients who underwent hematopoietic stem cell transplant (HSCT), but they provide broad timeframes for initiating vaccination; there is no standard schedule. The optimal approach to immunization in these populations is unclear. We sought to describe immunization practices at Canadian Pediatric Hematology/Oncology centers. A 43-item online questionnaire was distributed to the 16 programs in the C(17) research network of pediatric hematology/oncology centers to capture information on timing and criteria for immunization of patients with acute lymphocytic leukemia (ALL) and those who have undergone HSCT. At each center, 1-2 physicians or pharmacists completed the survey to reflect center-wide immunization practices. Responses were received from 11/16 (69%) programs; 11 respondents reported on practices for patients with ALL and 9 reported on practices for patients who are post-HSCT. In 5/11 ALL programs (45%) re-immunization is recommended routinely after chemotherapy, starting 3-6 months post-chemotherapy. In HSCT programs, timing of pneumococcal conjugate vaccination (PCV) varied from 3 months post-HSCT (4 programs) to 12 months post-HSCT (4 programs). Live vaccines were administered 24 months post-HSCT in 8/9 programs. All HSCT programs considered graft-versus-host-disease and 7 considered discontinuation of immunosuppression in immunization decisions. Pediatric hematology/oncology programs were divided in regards to re-immunization of patients with ALL post-chemotherapy. After HSCT, timing of PCV administration varied, with 4 programs initiating immunization later than Canadian guidelines recommend (3-9 months post-HSCT). These findings suggest a need to standardize immunization practices in these populations.

[Seroconversion in response to a reinforced primary hepatitis B vaccination in children with cancer]

INTRODUCTION

Immune response against vaccine antigens may be impaired in children with cancer. The aim of this study was to evaluate the seroconversion response against hepatitis B vaccination (HBV) at the time of chemotherapy onset and/or remission in children with cancer.

PATIENTS AND METHOD

Prospective, two-centre, controlled, non-randomised study conducted on children recently diagnosed with cancer, paired with healthy subjects. Cases received HBV at time 0, 1 and 6 months with DNA recombinant HBV at a dose of 20 and 40 μg if < or > than 10 years of age, respectively, at the time of diagnosis for solids tumours and after the remission in case of haematological tumours. Controls received the same schedule, but at of 10 and 20 μg doses, respectively. HBs antibodies were measured in serum samples obtained at 2, 8 and 12 months post-vaccination. Protective titres were defined as > 10 mIU/ml at 8th month of follow up.

RESULTS

A total of 78 children with cancer and 25 healthy controls were analysed at month 8th of follow up. Seroconversion rates in the cancer group reached 26.9%, with no differences by age, gender or type of tumour (P = .13, .29, and .44, respectively). Control group seroconversion was 100% at the 8th month, with P < .0001 compared with the cancer group. At month 12 of follow up, just 31.9% of children with cancer achieved anti-HBs antibodies > 10 mIU/ml.

CONCLUSIONS

Vaccination against hepatitis B with three doses of DNA recombinant vaccine at an increased concentration, administrated at the time of onset of chemotherapy and/or remission provided an insufficient immune response in a majority of children with cancer. More immunogenic vaccines should be evaluated in this special population, such as a third generation, with more immunogenic adjuvants, enhanced schedules at 0, 1, 2, 6 month, evaluation of antibody titres at month 8 and 12h to evaluate the need for further booster doses.

Pneumococcal conjugate vaccine administration during therapy for pediatric leukemia

BACKGROUND

Pediatric leukemia patients are at high risk of invasive pneumococcal disease. The study aim was to determine the antibody response to a 10-valent pneumococcal conjugate vaccine (PCV10) administered during chemotherapy.

METHODS

An open-label study in pediatric leukemia patients: Group 1 had completed a primary 7-valent (PCV7) course and received a single PCV10 dose. Group 2 were PCV immunization naïve and received 3 doses of PCV10, administered 2 months apart. Serum samples were taken at baseline and 1 month post each PCV10 dose. Antipneumococcal serotype-specific IgG to 10 serotypes were measured by enzyme-linked immunosorbent assay and the functional response to 4 serotypes (1, 6B, 19F and 23F) was measured using opsonophagocytic assays.

RESULTS

Thirty-nine participants were recruited between May 2010 and January 2011; group 1 (n = 27) and group 2 (n = 12). The diagnosis was acute lymphoblastic leukemia (38) and acute myeloid leukemia (1). Median age was 6.2 years (1.7-17.2 years) with 62% male. The median time from diagnosis to baseline serology was 7.4 months (1.6-36.8 months). At baseline, protective geometric mean concentration above the threshold (>0.35 μg/mL) ranged from 5.3% (serotype 4) to 71% (serotype 19F). More than 60% of participants in both groups were above threshold postimmunization for 7 of the 10 PCV serotypes. Opsonophagocytic assay correlated with enzyme-linked immunosorbent assay for 3 of the 4 serotypes and r ranged from 0.51 to 0.84. An injection-site reaction was reported in 73% (27/37).

CONCLUSIONS

It is safe to administer PCV10 vaccine during therapy for pediatric leukemia. It provided a satisfactory serum immune response for the majority of vaccine serotypes.

Immunologic effects of hydroxyurea in sickle cell anemia

BACKGROUND AND OBJECTIVE

Susceptibility to encapsulated bacteria is well known in sickle cell disease (SCD). Hydroxyurea use is common in adults and children with SCD, but little is known about hydroxyurea's effects on immune function in SCD. Because hydroxyurea inhibits ribonucleotide reductase, causing cell cycle arrest at the G1-S interface, we postulated that hydroxyurea might delay transition from naive to memory T cells, with inhibition of immunologic maturation and vaccine responses.

METHODS

T-cell subsets, naive and memory T cells, and antibody responses to pneumococcal and measles, mumps, and rubella vaccines were measured among participants in a multicenter, randomized, double-blind, placebo-controlled trial of hydroxyurea in infants and young children with SCD (BABY HUG).

RESULTS

Compared with placebo, hydroxyurea treatment resulted in significantly lower total lymphocyte, CD4, and memory T-cell counts; however, these numbers were still within the range of historical healthy controls. Antibody responses to pneumococcal vaccination were not affected, but a delay in achieving protective measles antibody levels occurred in the hydroxyurea group. Antibody levels to measles, mumps, and rubella showed no differences between groups at exit, indicating that effective immunization can be achieved despite hydroxyurea use.

CONCLUSIONS

Hydroxyurea does not appear to have significant deleterious effects on the immune function of infants and children with SCD. Additional assessments of lymphocyte parameters of hydroxyurea-treated children may be warranted. No changes in current immunization schedules are recommended; however, for endemic disease or epidemics, adherence to accelerated immunization schedules for the measles, mumps, and rubella vaccine should be reinforced.

Assessment of immune response following immunization with DTP/Td and MMR vaccines in children treated for acute lymphoblastic leukemia

BACKGROUND

This study was performed to determine the antibody titers against diphtheria-tetanus-pertussis, and measles-mumps-rubella before and after re-vaccination in different periods of time in patients with acute lymphoblastic leukemia (ALL) to provide a suitable vaccination schedule.

METHODS

Ninety patients with ALL were studied in three stages, including newly diagnosed patients, patients on maintenance therapy, and 1 to 12 months after cessation of therapy. Baseline antibody titers were assessed in all participants. Postimmunization antibody titers to DTP/Td and MMR vaccines were evaluated 3 weeks after vaccination.

RESULTS

Patients on maintenance therapy had considerable decreased in seropositivity rate; they achieved seroconversion rate of 100% for diphtheria and tetanus and of 71.4% for pertussis following DTP/Td vaccination. In patients after one month off therapy, the seroconversion rates for diphtheria, tetanus, and pertussis were 71.4%, 80%, and 100%, respectively. The amounts of seroconversion in patients after 3 months off therapy were 66.5%, 80%, and 66.5% for measles, mumps, and rubella, respectively. In patients after 6 months off therapy, the seroconversion rates were 85.7% for diphtheria, 100% for pertussis and tetanus, 83.3% for mumps, 50% for rubella, and 41.6% for measles. Patients after 12 months off therapy achieved seroconversion rate of 100% for diphtheria, tetanus, pertussis, and mumps, of 71.5% for rubella, and of 63.5% for measles.

CONCLUSION

Administration of one dosage of DTP/Td vaccine during maintenance therapy and after cessation of therapy could be recommended, while one dosage of MMR vaccine at least three months after completion of therapy could be safe and beneficial.

Guidelines on vaccinations in paediatric haematology and oncology patients

OBJECTIVE

Vaccinations are the most important tool to prevent infectious diseases. Chemotherapy-induced immune depression may impact the efficacy of vaccinations in children.

PATIENTS AND METHODS

A panel of experts of the supportive care working group of the Italian Association Paediatric Haematology Oncology (AIEOP) addressed this issue by guidelines on vaccinations in paediatric cancer patients. The literature published between 1980 and 2013 was reviewed.

RESULTS AND CONCLUSION

During intensive chemotherapy, vaccination turned out to be effective for hepatitis A and B, whilst vaccinations with toxoid, protein subunits, or bacterial antigens should be postponed to the less intensive phases, to achieve an adequate immune response. Apart from varicella, the administration of live-attenuated-virus vaccines is not recommended during this phase. Family members should remain on recommended vaccination schedules, including toxoid, inactivated vaccine (also poliomyelitis), and live-attenuated vaccines (varicella, measles, mumps, and rubella). By the time of completion of chemotherapy, insufficient serum antibody levels for vaccine-preventable diseases have been reported, while immunological memory appears to be preserved. Once immunological recovery is completed, usually after 6 months, response to booster or vaccination is generally good and allows patients to be protected and also to contribute to herd immunity.

Attenuated measles virus controls pediatric acute B-lineage lymphoblastic leukemia in NOD/SCID mice

Novel therapies are needed for pediatric acute lymphoblastic leukemia resistant to conventional therapy. While emerging data suggest leukemias as possible targets of oncolytic attenuated measles virus, it is unknown whether measles virus can eradicate disseminated leukemia, in particular pediatric acute lymphoblastic leukemia. We evaluated the efficacy of attenuated measles virus against a large panel of pediatric xenografted and native primary acute lymphoblastic leukemias ex vivo, and against four different acute lymphoblastic leukemia xenografts of B-lineage in non-obese diabetic/severe combined immunodeficient mice. Ex vivo, attenuated measles virus readily spread among and effectively killed leukemia cells while sparing normal human blood cells and their progenitors. In immunodeficient mice with disseminated acute lymphoblastic leukemia a few intravenous injections of attenuated measles virus sufficed to eradicate leukemic blasts in the hematopoietic system and to control central nervous system disease resulting in long-term survival in three of the four xenografted B-lineage leukemias. Differential sensitivity of leukemia cells did not require increased expression of the measles entry receptors CD150 or CD46 nor absence of the anti-viral retinoic acid-inducible gene I/melanoma differentiation associated gene-5 /interferon pathway. Attenuated oncolytic measles virus is dramatically effective against pediatric B-lineage acute lymphoblastic leukemia in the pre-clinical setting warranting further investigations towards clinical translation.

Impaired B-cell reconstitution in children after chemotherapy for standard or medium risk acute precursor B-lymphoblastic leukemia

Chemotherapy for childhood acute lymphoblastic leukemia (ALL) is a highly effective treatment, but at the same time causes significant suppression of the patient's immunity. Immune reconstitution was studied in a homogeneous cohort of 48 children with standard or medium risk ALL treated according to the ALL-Berlin-Frankfurt-Münster (BFM) protocol. Whereas the T-cell compartment was only moderately affected and recovered to normal levels quickly after treatment cessation, B-cells were significantly reduced during and after therapy. In particular, the naive B-cell compartment declined. Even 5 years after the end of therapy, B-cell distribution was disturbed and patients showed an ongoing reconstitution. Thus, even standard regimens for chemotherapy cause severe B-cell depletion that resolves only gradually.

Haemophilus influenzae type B in an immunocompetent, fully vaccinated ALL survivor

A 7-year-old boy with a history of recurrent acute lymphoblastic leukemia (ALL), in remission, presented to primary care clinic after 2 days of progressive right hip pain with weight-bearing activities. He was otherwise asymptomatic at the time of presentation. Blood cultures revealed Gram-negative diplococci, which prompted an MRI that was significant for a hip joint effusion and femoral head bone marrow edema. The patient had no sick contacts and no significant past medical history other than ALL. The patient had been given all recommended childhood vaccinations. Arthrocentesis and needle biopsy of the femoral neck were not diagnostic for malignancy and revealed only mild hip joint inflammation, leading to a diagnosis of osteomyelitis. The organism in the original blood culture was identified as Haemophilus influenzae type b, β-lactamase negative. Review of the patient's medical records showed a history of complete immunization to Haemophilus influenzae type b. An immunologic evaluation was made to determine if the patient retained immunity from his other vaccinations. Pathogen-specific antibody testing revealed detectable antibodies to polio but not measles, mumps, rubella, varicella-zoster virus, tetanus, diphtheria, pertussis, or hepatitis B. This loss of immunologic memory appears to be a rarely described side effect of ALL chemotherapy. There is currently no protocol to evaluate the immunologic memory of patients who underwent chemotherapy for ALL or to revaccinate them after their treatment. It is unclear whether the loss of immunologic memory is genuinely rare or is underdiagnosed because affected patients are protected by herd immunity.